1. Technical Field
The present invention generally relates to the field of water-based adhesives and more specifically relates to the field of high solids content, with no or minimal volatile organic compounds (VOC), adhesives suitable for packaging in pressurized containers to be later sprayed. The present invention further generally relates to the field of adhesive application systems and more specifically relates to the field of adhesive application systems comprising a pressurized container containing the adhesive and a propellant.
2. Prior Art
Traditional adhesive systems for packaging into a pressurized container such as an aerosol can or propane type cylinder, have been solvent-based compounds because of good solubility, low cost, solvency in standard pressure propellant systems such as propane, butane, and isobutene compounds and blends thereof, and in some cases high pressure propellant systems such as nitrogen and carbon dioxide. The majority of these traditional systems usually contain at least some VOCs or some level of flammability. Solvent-based systems also usually carry with them a number of undesirable health hazards, environmental concerns, or even the possibility of being explosive in nature. As local, state and national governmental regulations have been tightening the requirements for adhesives and other chemical-based products to contain less VOCs and to be more environmentally friendly, it has become almost necessary to research more environmentally friendly alternatives to adhesives.
Pressurized adhesive systems also have been developed using compressed air to atomize and spray the adhesive. These compressed air systems necessitate additional expense for spraying equipment, are bulky, and can be difficult to transport or clean up. Water-based systems also have been developed that incorporate traditional adhesive and propellant properties. However, incompatibility issues have arisen between the adhesive and the propellant system necessitating the need to use additional high-pressure propellants, which add a greater degree of danger, to obtain proper spray patterns or to get the adhesive to properly and completely spray out of the container. Coverage of these spray systems is only slightly better than the existing system of spreading the adhesive on the flooring surface with a trowel or other such device. Furthermore, these self-contained pressurized systems only can be packaged in a propane type cylinder that is designed for pressures up to 220-250 psi. Because of these high-pressure requirements, that type of system cannot be packaged into a traditional aerosol container.
Typical water-based latex emulsions also are used, but with limited success in a self-contained sprayable system. Also, the typical non-sprayable, and in some cases sprayable with non self-contained systems, adhesive market generally has been divided into two major categories. The first category comprises water-based emulsions based upon styrene butadiene rubber (SBR) latex for adhering materials such as general floor covering to wood, fiberglass or concrete surfaces and other like applications, and are less costly than other systems. These SBR-based systems are more common. The second category comprises acrylic-based formulas for mostly pressure sensitive applications. These acrylic-based systems typically are more costly.
Thus, it can be seen that there exists a need for an adhesive that can be applied to a surface using a low- or medium-pressure delivery system. There exists a further need for an adhesive that has a high solids content for superior adhesion qualities. There exists another need for an adhesive that has better water resistance when dry and a greater immunity to high alkalinity. There exists an additional need for an adhesive that contain no or minimal VOCs. It is to these exemplary needs, as well as other needs, that the present invention is directed.